Added the CallContract util

contracts/InterchainTokenServiceCallContract.sol

@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity ^0.8.0;
+
+import { InterchainTokenServiceVirtual } from './InterchainTokenServiceVirtual.sol';
+import { ICallContract } from './interfaces/ICallContract.sol';
+
+/**
+ * @title The Interchain Token Service
+ * @notice This contract is responsible for facilitating interchain token transfers.
+ * It (mostly) does not handle tokens, but is responsible for the messaging that needs to occur for interchain transfers to happen.
+ * @dev The only storage used in this contract is for Express calls.
+ * Furthermore, no ether is intended to or should be sent to this contract except as part of deploy/interchainTransfer payable methods for gas payment.
+ */
+contract InterchainTokenServiceCallContract is InterchainTokenServiceVirtual {
+    error CallContractFailed(bytes returnData);
+
+    address public immutable callContract;
+
+    constructor(
+        address tokenManagerDeployer_,
+        address interchainTokenDeployer_,
+        address gateway_,
+        address gasService_,
+        address interchainTokenFactory_,
+        string memory chainName_,
+        address tokenManagerImplementation_,
+        address tokenHandler_,
+        address callContract_
+    ) InterchainTokenServiceVirtual(
+        tokenManagerDeployer_,
+        interchainTokenDeployer_,
+        gateway_,
+        gasService_,
+        interchainTokenFactory_,
+        chainName_,
+        tokenManagerImplementation_,
+        tokenHandler_
+    ) {
+        if(callContract_ == address(0)) revert ZeroAddress();
+
+        callContract = callContract_;
+    }
+
+    /**
+     * @notice Calls a contract on a specific destination chain with the given payload
+     * @param destinationChain The target chain where the contract will be called.
+     * @param payload The data payload for the transaction.
+     * @param gasValue The amount of gas to be paid for the transaction.
+     */
+    function _callContract(
+        string calldata destinationChain,
+        bytes memory payload,
+        ICallContract.MetadataVersion metadataVersion,
+        uint256 gasValue
+    ) internal override {
+        string memory destinationAddress = trustedAddress(destinationChain);
+        (bool success, bytes memory returnData) = callContract.delegatecall(abi.encodeWithSelector(
+            ICallContract.callContract.selector, 
+            destinationChain,
+            destinationAddress,
+            payload,
+            metadataVersion,
+            gasValue
+        ));
+
+        if(!success) revert CallContractFailed(returnData);
+    }
+
+    /**
+     * @notice Calls a contract on a specific destination chain with the given payload and gateway token
+     * @param destinationChain The target chain where the contract will be called.
+     * @param payload The data payload for the transaction.
+     * @param symbol The gateway symbol of the token.
+     * @param amount The amount of token transfered.
+     * @param metadataVersion The metadata version
+     * @param gasValue The amount of gas to be paid for the transaction.
+     */
+    function _callContractWithToken(
+        string calldata destinationChain,
+        bytes memory payload,
+        string memory symbol,
+        uint256 amount,
+        ICallContract.MetadataVersion metadataVersion,
+        uint256 gasValue
+    ) internal override {
+        string memory destinationAddress = trustedAddress(destinationChain);
+        (bool success, bytes memory returnData) = callContract.delegatecall(abi.encodeWithSelector(
+            ICallContract.callContractWithToken.selector, 
+            destinationChain,
+            destinationAddress,
+            payload,
+            symbol,
+            amount,
+            metadataVersion,
+            gasValue
+        ));
+
+        if(!success) revert CallContractFailed(returnData);
+    }
+}